Torque balancing linkage for excavator dipper sticks

ABSTRACT

A dipper stick is adjustably mounted in a saddle which is pivoted to upstanding brackets at the outer end of the boom of an excavating machine, there being an hydraulic cylinder pivoted at one end to the boom and having a piston rod projecting from its other end and connected to the lower converging ends of two sets of links. One set of links acts as a radius rod and has its upper ends pivotally connected to upper portions of the boom brackets inwardly of the pivotal connection for the saddle, and the other set of links has its upper ends pivotally connected to the saddle outwardly of the pivotal connection for the saddle.

0 United States Patent [in 3,627,156

[72] Inventor Roy 0. Billings 3,143,228 8/1964 Billings 2 l4/l47 6621West Wisconsin Ave., Milwaukee, 3,220,578 1 1/1965 Pilch 214/138 Wis.53213 3,253,724 5/1966 Marner 214/138 [2]] Appl 859361 PrimaryExaminer-Gerald M Forlenza [22] Flled Sept 1969 AssistantExaminer.lerold M. Forsberg [45] Patented 1971 Attorney-Morse" & Morsell[541 TQRQUE BALANCING LINKAGE FOR ABSTRACT: A dipper stick is adjustablymounted in a saddle EXCAVATOR F STICKS which is pivoted to upstandingbrackets at the outer end of the 1 Claim 5 Drawing boom of an excavatingmachine, there being an hydraulic [52] [1.8. Ci 214/147 G, Cylinderpivoted at one end to the boom and having a piston 214/]35 rodprojecting from its other end and connected to the lower [51] Int, ClB66 1/00 converging ends of two sets of links. One set of links acts asa 50] Field of Search 2 14/135, radius rod and has its upper endspivotally connected to upper 137, 138, 147 portions of the boom bracketsinwardly of the pivotal connection for the saddle, and the other set oflinks has its upper ends References Cited pivotally connected to thesaddle outwardly of the pivotal con- UNITED STATES PATENTS nection forthe saddle. 3,l29,83l 4/1964 Mrozek 2l4/l37 BMZTIASG Patented Dec. 14,1971 3 Sheets-Sheet 1 INVENTOR ROY O BILLINGS 4% ATTORNEYS Patented Dec.14, 1971 3 Sheets-Sheet 2 INVENTOR ROY O. BILLINGS BY MW ATTORNEYSPatented Dec. 14, 1971 3 Sheets-Shoot (6 ATTORNEYS BACKGROUND OF THEINVENTION 1. Field of the Invention The invention is adapted for use inexcavating machines of the type having a clipper stick for supporting aclamshell bucket or other earth moving device.

2. Description of the Prior Art For many years the crowd" motion of adipper stick has been under the control of cables operated from the cab.Typical of this type of construction is Darrah, US. Pat. No. 1,954,119.In my prior US. Pat. Nos. 3,219,212, 3,143,228 and 3,143,229, hydraulicrams are employed and there are crowd" cylinders having lower endspivotally connected to the boom and having extensible rods with outerends pivotally connected directly to the dipper stick saddle. With thistype of arrangement, as the dipper stick saddle swings on its pivotrelative to the boom to raise the dipper stick toward a position whereit effects a greater angle with respect to the boom, the effectiveleverage of the crowd cylinder rod lessens as the dipper stick iselevated so that when the dipper stick is pushed upwardly from a normalworking position the effective leverage is the poorest, this being at atime when the torque demand is the greatest. Thus it has been necessaryto use an hydraulic cylinder of relatively large size to producesufficient power. Furthermore, with the arrangement of my prior patents,in certain positions of adjustment, excessive strains are placed uponthe outer end of the cylinder. In addition, with the arrangement of myprior patents, the cylinder has, in certain positions of adjustment,protruded from the lower portion of the boom. Such protrusion isundesirable as there is a possibility of damage to the cylinder duringoperation.

SUMMARY OF THE INVENTION The present invention includes, in anexcavating device being a boom with a dipper stick saddle pivoted toupstanding brackets near its outer end, and having a crowd cylinderpivotally connected at its head end to the boom and having a piston rodprojecting from its opposite end, torque balancing linkage connectedbetween the end of the rod and the boom brackets and saddle and arrangedto equalize stresses during the crowd" action and to maintain thehydraulic thrust closer to a straight line action.

A general object of the invention is to provide, in a device of theclass described torque balancing linkage arranged to minimize thereduction in leverage which normally occurs when the dipper stick isbeing swung toward a position of parallelism with the boom.

A further object of the invention is to provide torque balancing linkagewhich minimizes the amount of swing of the hydraulic cylinder duringoperation whereby the cylinder maintains a position substantially withinthe confines of the boom.

A further object of the invention is to provide torque balancing linkagefor controlling the dipper stick movement which is arranged to provideincreased leverage When it is most needed, thereby permitting efficientoperation even when the dipper stick is in its maximum extended positionin the saddle.

A further object of the invention is to provide, in a device of theclass described, improved torque balancing linkage which makes itpractical to employ a crowd" cylinder of less size than would otherwisebe necessary.

A further object of the invention is to provide, in a device of theclass described, improved torque balancing linkage which maintains theeffective lever arm" for controlling the crowd" action of the dipperstick closer to a constant length throughout the entire stroke of thecrowd" cylinder.

With the above and other objects in view, the invention consists of theimproved torque balancing linkage for excavator dipper sticks, and allof its parts and combinations, as set forth in the claims, and allequivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings,designating one complete embodiment of a preferred form of theinvention, in which the same reference numerals designate the same partsin all of the views:

FIG. 1 is a side elevational view ofan earth working device of a typehaving an adjustable dipper stick supporting a clamshell bucket;

FIG. 2 is a fragmentary side elevational view showing the outer end ofthe boom, and showing; a portion of the dipper stick extending throughthe saddle, the saddle and dipper stick being in a position close toparallelism with the boom;

FIG. 3 is a bottom plan view of the structure illustrated in FIG. 2, thedipper stick being omitted;

FIG. 4 is a view similar to FIG. 2 showing the saddle swung to anintermediate position which is advanced in a downward direction from theposition of FIG. 1, parts being broken away; and

FIG. 5 is still another view showing the saddle in an extreme crowd"position with the ram fully retracted.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly tothe drawings, the numeral 20 designates the tractor portion of an earthworking device, which device has a turntable 21 supporting a pivotedboom 22, there being an hydraulic cylinder 23 having a telescopic pistonrod 2d pivoted at its outer end to the boom for controlling the boomangle.

As is clear from FIG. 3 the boom includes spaced side members 25 andprojecting upwardly from the top of each side member is an upstandingbracket 26, as shown in FIG. 2. A pivot pin 27 which connects upperforward portions of the brackets 26 serves as the means by which asaddle 28 is pivotally supported on the boom 25 in the manner shown inFIGS. 2 and 3. The ends of the pin 27 extend through the lower ends ofreinforcing ribs 29 on side portions 30 of the saddle, the saddle beinggenerally U-shaped in cross section as shown in FIG. 3. A fluid pressureoperated cylinder 31 has its head end pivotally connected between thesides 25 of the boom as at 32 (FIG. 1). The cylinder has a telescopicpiston rod 33 projecting from the usual hydraulically actuated piston.This cylinder may be hereinafter termed a crowd" cylinder, and isoperated in the usual manner under control of a valve in the cab.

Adjustably mounted in the saddle for extensible movement is a dipperstick 34 which adjustably carries an earth working tool such as aclamshell bucket 35 on its lower end. Any suitable means may be providedfor causing extension and retraction of the dipper stick 34 in itssaddle 28. Inasmuch as this forms no part of the present invention theoperating mechanism for such extensible movement will not be described.

Torque Balancing Linkage Radius links 36 have upper ends rigidlyconnected to a sleeve 37 which is adapted to rock on a pivot rod 38which connects upper rear portions of the brackets 26. The lower ends ofthe links are connected by a crank pin 39 which extends through abearing 40 at the outer end of the piston rod 33. Thus the radius rodsmaintain the pin 39 in the path of the arc a during movement of thepiston rod 33 and it is to be noted that the are a is substantiallywithin the confines of the boom. Power-transmitting links 41 have theirupper ends pivoted on a pin 42 which extends between the sides 30 of thesaddle 28. The lower ends of the links 41 are pivoted to the outer endof the piston rod 33 and to the lower ends of the radius links 36 bymeans of the pin 39, as shown in FIGS. 2 and 3.

Projecting downwardly beyond the sides of the saddle are stopprojections 43 having end recesses 44 shaped to fit the boom bosses 45(HQ 3) when the dipper stick is in the fully elevated position of FIG.2. These extensions form a suitable stopagainst further movement. Otherconvenient stop arrangements may of course be employed.

OPERATION When it is desired to crowd" the dipper stick the fluidpressure operated ram may be actuated,,through any suitable controlvalves in the cab, to cause retraction of the piston rod 33 from thefully extended position of FIG. 2. During such action the ram 33 willexert a pull to the left on the lower end of the links 41 and, due tothe radius links 36, the pivot point 39 will travel in the are a. FIG. 1shows a position wherein the dipper stick is swung slightly downwardlyfrom the position of FIG. 2. Further retraction of the ram will bringthe dipper stick to the angular position shown in FIG. 4 which is atypical working position. FIG. shows a fully crowded position where theram is completely retracted in the cylinder 31.

During reverse or elevated movement of the dipper stick the improvedlinkage creates maximum leverage when most needed. At the start ofextension movement of the ram from the position of FIG. 5 there will bea push exerted on the pivot point 42 through the linkage 41. As theextension continues the parts will assume the position shown in FIG. 4.Further movement will bring the parts to the position of FIG. 1, andstill further movement to the final position of FIG. 2. According toprior practices where the piston rod 33 was connected directly to asaddle, there was the problem of interference from the saddle pivot 27,and during movement from the position of FIG. 4 to the position of FIG.2 where the torque demand is the greatest, the effective leverage hasdecreased.

With the present invention, due to the novel linkage arrangement, theeffective lever arm indicated at b in FIGS. 2, 4 and 5 is maintained ata substantial length through the range of movement. This distance b isthe distance of the pivot point 27 above the axis of the piston rod 33,measured as indicated at b. It will be noted from FIG. 5 that in thefully crowded position the distance b is at its minimum. However, it isstill of substantial length and on extension movement of the piston rodfrom the position of FIG. 5 there is a minimum power demand at thestart. When the dipper stick arrives at approximately the position ofFIG. 4 the lever arm" distance b is the largest and this is highlydesirable because in swinging the dipper stick upwardly from theposition of FIG. 4, with the clamshell bucket loaded, a maximum amountof power is required. This lever arm" distance b, of course, diminishesat the extreme position shown in FIG. 2, but it is seldom necessary toswing the dipper stick as far as the position of FIG. 2. Furthermore, inall of the positions illustrated, including the position of FIG. 2, theI ever arm length b is nevertheless substantial. With priorconstructions, where there was a direct connection between the end ofthe piston rod 33 and the saddle, effective leverage diminished tonearly zero in the position of FIG. 2. With this arrangement the rammaintains a substantially straight thrust in all portions of movement.It is also apparent from FIGS. 2, 4 and 5 that the cylinder 31 pivotsonly a minor amount on its pivot 32 and always stays substantiallywithin the confines of the boom. By maintaining a relatively straightthrust, and a minimum amount of pivot movement of the cylinder there isless stress on the end of the cylinder during operation. The improvedtorque balancing linkage equalizes stresses throughout the range ofmovement. As a result a smaller cylinder 31 may be employed than wouldotherwise be necessary, and the device will still have ample power toelevate the dipper stick when the bucket is filled and when the dipperstick is in an extended position. With prior arrangements there wassubstantially reduced leverage just when the demand was greatest.

It is to be understood that I do not desire to be limited to the exactdetails of construction shown and described, for obvious modificationswill occur to a person skilled in the art.

What I claim is:

1. In an earth moving machine having a boom with spaced side members atits outer end, said side members having spaced upstanding outer endprojections, a saddle pivotally connected between said space upstandingpro ections of the side members of the boom to normally projectthereabove, a dipper stick slideably adjustably carried in said saddle,a fluid pressure operated cylinder pivotally connected at its inner endto the boom to extend generally longitudinally thereof and having anextensible piston rod projecting outwardly toward the outer end of theboom, the improvement comprising power-transmitting linkage pivotallyconnected at one end to the piston rod and at its other end to thesaddle at a location above the piston rod and spaced longitudinallyoutwardly from the pivotal connection between the saddle and theupstanding projections of the boom, radius linkage pivotally connectedat its upper end to the upstanding projections of the boom inwardly ofthe pivotal connection between the saddle and said projections andhaving its lower end connected to the piston rod adjacent the pivotalconnection between the piston rod and said power-transmitting linkage,both the powertransmitting linkage and the piston rod extending in thesame general as the longitudinal axis of the boom when the dipper stickis in an inwardly crowded position, and the power-transmitting linkagebeing movable upwardly at a progressively increasing angle with respectto the axis of the boom as the dipper stick is raised whereby theeffective lifting force from the piston rod is augmented as the demandfor power increases during elevation of the dipper stick and saddle to aposition of parallelism with the boom, wherein, when the piston rod isfully extended, the length and position of the radius linkage is such asto maintain the cylinder and its piston rod substantially within theconfines of the side members of the boom while the dipper stick issubstantially parallel with the boom, and wherein the length andposition of the radius linkage is such as to maintain the arc ofswinging movement of the pivotal connection between the end of thepiston rod and the linkage such that said pivotal connection stayssubstantially within the confines of the side members of the boom in allpositions of movement.

t i i t i

1. In an earth moving machine having a boom with spaced side members atits outer end, said side members having spaced upstanding outer endprojections, a saddle pivotally connected between said spaced upstandingprojections of the side members of the boom to normally projectthereabove, a dipper stick slideably adjustably carried in said saddle,a fluid pressure operated cylinder pivotally connected at its inner endto the boom to extend generally longitudinally thereof and having anextensible piston rod projecting outwardly toward the outer end of theboom, the improvement comprising power-transmitting linkage pivotallyconnected at one end to the piston rod and at its other end to thesaddle at a location above the piston rod and spaced longitudinallyoutwardly from the pivotal connection between the saddle and theupstanding projections of the boom, radius linkage pivotally connectedat its upper end to the upstanding projections of the boom inwardly ofthe pivotal connection between the saddle and said projections andhaving its lower end connected to the piston rod adjacent the pivotalconnection between the piston rod and said power-transmitting linkage,both the power-transmitting linkage and the piston rod extending in thesame general direction as the longitudinal axis of the boom when thedipper stick is in an inwardly crowded position, and thepower-transmitting linkage being movable upwardly at a progressivelyincreasing angle with respect to the axis of the boom as the dipperstick is raised whereby the effective lifting force from the piston rodis augmented as the demand for power increases during elevation of thedipper stick and saddle to a position of parallelism with the boom,wherein, when the piston rod is fully extended, the length and positionof the radius linkage is such as to maintain the cylinder and its pistonrod substantially within the confines of the side members of the boomwhile the dipper stick is substantially parallel with the boom, andwherein the length and position of the radius linkage is such as tomaintain the arc of swinging movement of the pivotal connection betweenthe end of the piston rod and the linkage such that said pivotalconnection stays substantially within the confines of the side membersof the boom in all positions of movement.